On Wed, Jun 17, 2020 at 1:19 PM Hal <hwang....@gmail.com> wrote:
> * the syntax defining generic function is verbose on purpose (type
> keyword), not only for clarification, but also a remind of the cost and
> complexity behind generics
>
I don't know where this idea is from, but it's not accurate. The type
keyword is there to resolve a syntactical ambiguity: Without it, you
couldn't tell if `func F(A) (B)` is a function taking an A and returning a
B, or a generic function with type-parameter A and argument B.
The design draft actually opts to *not* be overly verbose, e.g. by omitting
the `type` keyword and constraints in method receivers of generic types.
* normal parameter list does not support default type, to be consistent,
> type parameter list should not either
>
I think it's fair to say that there is a semantical asymmetry here, in that
while there is a natural choice for a default constraint (namely being
unconstrained), there isn't one for parameter-types.
* multiple generic types without constraints can be written as "type T1,
> T2, T3 interface{}", not too much boilerplate anyway
>
I think in practice, something else would happen in many cases: Authors
would want a shorter way to write this, so packages would start declaring
`type Any interface{}` and use `Any` as a constraint - or use any of a
dozen or so names for the concept.
This isn't a deal-breaker to me, either way. But I don't really see a good
reason to forego this obvious small quality-of-life improvement. It's
pretty clear what it means to have no constraint anyway.
>
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